Medical Retrieval Devices

ABSTRACT

A medical retrieval device may include an elongated member having first and second end portions and a middle portion. The elongated member may be configured such that the first and second end portions are proximal one another and extend substantially parallel to one another along a longitudinal axis. The middle portion may have an unconstrained basket configuration. A first sheath may be configured to receive at least a portion of the first end portion, and a second sheath may be configured to receive at least a portion of the second end portion. At least one of the first and second sheaths may be movable relative to the middle portion so as to constrain the middle portion in an elongated configuration.

This application is a continuation of U.S. patent application Ser. No. 12/439,144, which was filed as a U.S. national stage application under 35 U.S.C. § 371 of International Patent Application No. PCT/US2007/076984, filed Aug. 28, 2007, claiming priority to U S. Provisional Application No. 60/823,681, filed Aug. 28, 2006, each of which is incorporated by reference in its entirety into this application.

The present invention relates to medical retrieval devices. More particularly, the present invention relates to medical retrieval devices and methods utilizing a retrieval device to remove stone fragments from a body lumen.

Some conventional instruments for kidney stone removal include a basket or forceps for grabbing a stone. Such instruments may be used to remove a smaller stone in one piece. However, for larger stones, a surgeon (e.g., a urologist) typically uses a laser or other instrument to first break up the larger stone into a number of fragments before attempting removal. Because of the size and/or operation of conventional baskets and forceps, the surgeon cannot remove the fragments at the same time. Instead, the surgeon typically has to remove the instrument from the patient each time a fragment is removed and then re-introduce the instrument for each additional fragment.

In addition, during the fragmentation step of a conventional ureteroscopic procedure, some fragments often migrate, for example, back toward the kidney. The migration may be due to contact with a laser fiber or as a result of pressures created during fragmentation.

It may be desirable to provide a retrieval device capable of retrieving and removing a plurality of stones and/or fragments with one removal from the body lumen. It may be desirable to provide a retrieval device capable of maintaining the position of a stone and/or fragments during a fragmentation process.

The medical retrieval devices and methods of the present invention may solve one or more of the problems set forth above.

According to various aspects of the disclosure, a medical retrieval device may include an elongated member having first and second end portions and a middle portion. The elongated member may be configured such that the first and second end portions are proximal one another and extend substantially parallel to one another along a longitudinal axis. At least one sheath may be configured to receive at least a portion of the end portions. For example, the device may comprise two sheaths, with one sheath enclosing each end portion. Alternatively, a single sheath may enclose both end portions. A handle portion may be associated with the elongated member and the sheath. The handle portion may be operable to cause relative movement between the sheath and the elongated member.

In accordance with various aspects of the disclosure, an exemplary method of removing an object from a body lumen may include positioning a medical device in a body lumen such that a distal end of the medical device is located at a desired position relative to at least one object to be removed. For example, the distal end of the medical device can be positioned distal to the object to be removed. According to various embodiments, the medical device includes a sheath and an elongated member. The method may include moving at least one of the end portions of the elongated member relative to the sheath so as to de-constrain a middle portion of the elongated member, and withdrawing the medical device from the body lumen to remove the at least one object.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a medical retrieval device with an exemplary elongated member in a first configuration in accordance with exemplary aspects of the present invention.

FIG. 2 is a perspective view of the elongated member of the medical retrieval device of FIG. 1.

FIG. 3 is an end view of the elongated member of FIG. 2.

FIG. 4 is an internal view of the handle and slide mechanism of the medical retrieval device of FIG. 1.

DETAILED DESCRIPTION

An exemplary embodiment of a medical retrieval device 100 is illustrated in FIGS. 1-4. The medical retrieval device 100 may include an elongated member 102 having an unconstrained configuration in the shape of a basket. The medical retrieval device 100 may have a distal end 110 and a proximal end 112, a handle portion 130, and an actuating member 103. According to various embodiments, the actuating member 103 is configured to be a thumb slide.

According to various aspects, the elongated member 102 may comprise a memory alloy such as, for example, nitinol. According to some aspects, the elongated member 102 may be a single wire or tube. According to various aspects, the elongated member 102 may comprise a laser resistant material such as, for example, a refractory metal, such as tungsten, so as to prevent the elongated member 102 from fragmenting if struck by a laser beam. According to various embodiments, and as best illustrated in FIG. 3, the elongated member 102 is encased in a flexible tungsten spring coil 101, which can prevent, or at least reduce the likelihood, of the elongated member 102 from fragmenting if struck by a laser beam.

Referring to FIG. 2, the elongated member 102 may comprise a first end portion 104, a second end portion 106, and a middle portion 108. According to various embodiments, the diameter of middle portion 108 can range from 5 to 25 mm, such as from 8 to 15 mm, for example 10 mm. End portion 102 is comprised of nitinol wire, and is wrapped by a laser-resistant tungsten coil 101. The elongated member 102 may be configured such that the first end portion 104 and second end portion 106 are proximal one another and extend substantially parallel to one another for at least a portion of their length. End portions 102 and 104 terminate in a joint 105. According to various embodiments, the joint 105 is constructed of a material other than nitinol, such as stainless steel. The termination joint has a first end 107, and a second end 109 (FIG. 4).

The middle portion 108 of elongated member 102 may be configured as a basket when unconstrained. For example, the middle portion 108 may comprise a portion of the elongated member 102 formed into a spiral shape, a conical shape, a “strain sensor” shape, a mesh, or the like. According to various aspects, the middle portion 108 may be constrained into an elongated configuration for introduction into and placement in a body lumen, for example a ureter.

Referring again to FIG. 1, the retrieval device 100 may include at least one sheath 120. The sheath 120 has an internal diameter sufficient to enclose first and second end portions 104 and 106 of the elongated member 102 (enclosed within tungsten coil 101). The sheath 120 may comprise a lubricious coating material such as, for example, PTFE. The sheath has a first end 111, and a second end (not shown) fixed in anchor 114 (FIG. 4). According to some aspects, the sheath 120 may have an outside diameter substantially equal to 3 Fr According to various embodiments, sheath 120 may comprise a single lumen through which the elongated member travels, or multiple lumens through which first and second ends 104 and 106 travel.

The retrieval device 102 may include a handle portion 130 proximal the sheath 120. The handle portion 130 may include one or more mechanisms configured to facilitate placement and deployment of the middle portion 108 of the elongated member 102 at a desired position in a body lumen. For examples the handle portion 130 may include an actuation mechanism 132 (FIG. 4) configured to slide the paired ends 104 and 106, and sheath 120 without relative movement to one another so that the distal end 110 of the retrieval device 100 may be at a desired position in a body lumen.

The handle portion 130 may include one or more gears (not shown) with the actuation mechanism 132. The one or more gears may cooperate with the actuation mechanism 132 to ensure that the distal end 110 of the elongated member 102 remains substantially at the point of placement for a desired period of time without relative movement between the elongated member 102 and the body lumen.

With the distal end 110 of the elongated member 102 placed at the desired location, the actuation mechanism 132 may cooperate to deploy the elongated member 102 from the sheath 120. For example, selective operation of the actuation mechanism 132 may cause the first and second ends 104, 106 to slide relative to the sheath 120, such that the middle portion 108 is permitted to move from the constrained configuration to the unconstrained configuration.

According to various aspects, the actuation mechanism 132 (shown in FIG. 4) may be configured such that the elongated member 102 is removed from the sheath 120 at a greater rate than that at which the sheath 120 is withdrawn relative to the desired position in the body lumen. For example, according to some aspects, the elongated member may be advanced from the distal end of the sheath 120 at a rate approximately two to three times greater than the rate at which the sheath is withdrawn proximally from the body lumen. The rate differential can be suitable because the length of wire of the middle portion 108 needed to form a basket configuration is greater than the length of wire required for positioning the device 100.

In operation, an elongated member 102 having an unconstrained configuration with a middle portion in the form of, for example, a basket, may be constrained into a substantially elongated configuration by the sheath in FIG. 2. For example, the first and second ends 104, 106 of the elongated member 102 may be withdrawn into sheath 120. In addition, at least a portion of the middle portion 108 may be withdrawn into the sheath such that a transverse dimension of the middle portion 108 is reduced to a size substantially similar to or less than a transverse dimension of the sheath 120.

Once constrained, the sheath 120 and elongated member 102 may be positioned at a desired location of a body lumen, for example, a ureter. The placement of the sheath 120 and elongated member 102 may be facilitated, for example, by the actuation mechanism 132 or other mechanical device associated with the handle portion 130. With reference to FIG. 4, actuating member 103 is attached to belt 115 having a slot 116. Anchor 113 fixes elongated member 102, and anchor 114 fixes sheath 120. Anchors 113 and 114 are each fixed to belt 115, which in turn is looped around distal cylindrical member 117 and proximal cylindrical member 118. When actuation member 103 (which may be a thumb slide) is moved in the proximal direction, the top of belt 115 moves in a proximal direction. Anchor 113, and thus elongated member 102 also move proximally, and anchor 114 and sleeve 120 move distally. Slot 116 also moves distally, allowing the elongated member 102 and sheath 120 to travel therethrough.

According to various aspects of the disclosure, a distal end of the constrained elongated member 102 may be positioned upstream (with respect to typical urine flow) of one or more kidney stones and/or fragments.

According to some aspects, for example, when the stone(s) and/or fragment(s) are sufficiently small so as not to damage the ureter during removal, the middle portion 108 of the elongated member 102 may be deployed by withdrawing the middle portion 108 from first the sheath 120, thereby allowing the middle portion 108 to achieve its unconstrained configuration, such as, for example, a basket. The sheath 120 and the elongated member 102 may then be withdrawn from the ureter and from the body, removing all stones and/or fragments along the path of withdrawal.

According to various aspects, for example, when at least one of the stone(s) and/or fragment(s) is sufficiently large that damage to the ureter during removal becomes an undesirable risk, a surgeon may first fragment the large stone(s) or fragment(s). The fragmentation may be achieved with, for example, a laser such as a holmium laser or any other laser.

Before fragmentation, the middle portion 108 of the elongated member 102 may be deployed upstream of the stone(s) and/or fragment(s) to prevent migration of fragments upstream during the fragmentation procedure. Once fragmented, the sheath 120 and the elongated member 102 may then be withdrawn from the ureter and from the body, removing all stones and/or fragments along the path of withdrawal.

It will be apparent to those skilled in the art that various modifications and variations can be made in the medical retrieval devices and methods of the present invention without departing from the scope of the invention. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only. 

1. A medical retrieval device, comprising: an elongated member having a middle region defining, in an unconstrained state, a basket configured to capture a kidney stone or a fragment thereof, the middle region located between side-by-side first and second end regions extending parallel to a longitudinal axis; a sheath substantially surrounding the elongated member in a constrained state, at least a portion of the middle region having a transverse dimension substantially similar to or less than a transverse dimension of the sheath; and a handle including an actuation mechanism connected separately to a proximal end of the sheath and a proximal end of the elongated member, the actuation mechanism enabling simultaneous translation of the sheath in a first direction and the elongated member in a second direction opposite of the first direction.
 2. The device according to claim 1, wherein the sheath constrains the middle region into a substantially elongated configuration in the constrained state.
 3. The device according to claim 1, wherein the actuation mechanism includes a slide mechanism coupled to a belt, and wherein the proximal end of the sheath and the proximal end of the elongated member are coupled to the belt.
 4. The device according to claim 3, wherein the proximal end of the sheath and the proximal end of the elongated member are fixed to respective first and second anchors fixed to the belt.
 5. The device according to claim 1, wherein the actuation mechanism enables distal advancement of the elongate member at a first rate greater than a second rate of proximal withdrawal of the sheath.
 6. The device according to claim 1, wherein the elongated member comprises a refractory metal wire wrapped around a shape memory metal wire along at least the middle region.
 7. The device according to claim 6, wherein the refractory metal is tungsten and the shape memory metal is nitinol.
 8. The device according to claim 1, wherein the first and second end regions are joined, respectively, to first and second proximal extension members extending in parallel relation to the proximal end of the elongated member.
 9. The device according to claim 8, wherein the elongated member comprises a refractory metal wire wrapped around a shape memory metal wire from the first end region to the second end region.
 10. The device according to claim 9, wherein the refractory metal is constructed of tungsten, wherein the shape memory metal is constructed of nitinol, and wherein the first and second proximal extension members are constructed of a material other than nitinol.
 11. The device according to claim 10, wherein the first and second proximal extension members are constructed of stainless steel.
 12. The device according to claim 1, wherein the basket forms a spiral shape.
 13. The device according to claim 12, wherein the basket lies along a plane perpendicular to the longitudinal axis.
 14. The device according to claim 1, wherein the sheath comprises polytetrafluoroethylene (PTFE). 